In the United States and other countries, end stage liver disease due to infection, genetic defects or alcoholic consumption is a major cause of widespread morbidity and mortality, causing great potential hardship and economic loss to millions of people throughout the world. In addition, numerous other diseases, including biliary problems and blood disorders, are associated with disruptions in the many functions carried out by the liver, including iron transport, hepatocyte formation and hematopoiesis. In general, severe problems associated with a breakdown of liver function are practically untreatable, and require a liver transplant as the only cure. However, in light of the great disparity between the number of patients needing liver transplants and the number of donors, thousands upon thousands of people are denied this operation, and transplantation is at the present time not a practical approach to the problem.
At the same time, the precise nature of liver development and the role of early developing liver proteins has not been well understood. To date, no growth factors specific to the liver have been identified or isolated, and the precise molecular mechanisms behind hepatocyte (liver cell) formation remain to be elucidated. There thus has been a long felt need to identify and understand the changes in gene regulation and expression in the developing liver, including the determination as to which genes are switched on and off as a hepatocyte forms and a liver develops. Accordingly, isolating and identifying the genes and proteins which play critical roles in early liver development would be beneficial in understanding the effect of gene regulation and expression in the differentiating liver, and in diagnosing and treating many diseases states involving the liver and liver functions.